Long form of this Swift syntax

Question

The following will compare the first element's id with compr's id, and return true if matched. I am confused with {} of .first { } != nil syntax. How does the longer form of this pattern condense to to the following:

private(set) var arr : [Arrs] = [] 

func isPresent(for compr: Compr) -> Bool {
  Arrs.first { comp.id == $0.id } != nil 
}

`first` returns `nil` if it doesn't find anything. So if the return value isn't `nil` it did find a value. — lorem ipsum, Oct 10 '21 at 16:58
`Arrs.first` doesn't compile. You certainly mean `arr.first` — vadian, Oct 10 '21 at 17:03
It would be simpler to use `contains(where:)`, see for example [Shorthand to test if an object exists in an array for Swift?](https://stackoverflow.com/q/29679486/1187415) — Martin R, Oct 10 '21 at 17:10

score 3 · Answer 1 · answered Oct 10 '21 at 17:16

First, change the line to the following so it compiles:

arr.first { compr.id == $0.id } != nil

This is just using trailing closure syntax for the first(where:) method. It can also be written as:

arr.first(where: { compr.id == $0.id }) != nil

But a better way would be to do the following:

arr.contains { compr.id == $0.id }

Long form of this Swift syntax

1 Answers1